The timefleas have been hopping around the web in search of an elegant, open and attractive solution for charting reports for our eventengine product.
There were many options which used jscript to create charts that we landed on, but most of them presented challenges in integration like the ability to only show a single chart or complexities when combined with the CSS and AJAX code we use. They usually also came with an additional cost if you wanted the full functionality.
The Google chart api allows you to request up to 50,000 charts via their api per 24hour period. In an eggshell, it provides a method to send your data in the form of a simple chart definition and it returns a JPG image. The JPG chart can have all the colours and design (Pie, 3d, stack, etc) injected into the API call, so once you have a standard method for making the request you can start to define some smart looking results.
Google PIE Chart
More details can be found here: http://code.google.com/apis/chart
Here is another sample chart, using some data from our eventengine product and a stacked bar view.
